Messages in this thread | | | Date | Tue, 11 Sep 2018 15:50:04 +0200 | From | Peter Zijlstra <> | Subject | Re: [PATCHv3 6/6] tty/ldsem: Decrement wait_readers on timeouted down_read() |
| |
On Tue, Sep 11, 2018 at 02:33:22PM +0100, Dmitry Safonov wrote: > > > You might want to think about ditching that ldsem thing entirely, > > > and use a regular rwsem ? > > > > Yeah, but AFAICS, regular rwsem will need to have a timeout then (for > > write). So, I thought fixing this pile would be simpler than adding > > timeout and probably writer-priority to generic rwsem? > > > > And I guess, we still will need fixes for stable for the bugs here.. > > > > I expect that timeouts are ABI, while the gain of adding priority may > > be measured. I'll give it a shot (adding timeout/priority for linux- > > next) to rwsem if you say it's acceptable. > > Actually, priority looks quite simple: we can add writers in the head > of wait_list and it probably may work. > Timeout looks also not a rocket science. > So, I can try to do that if you say it's acceptable (with the gain > measures).
So why do you need writer priority? The comment that goes with ldsems doesn't explain I think, it just says it has it.
In general I dislike unfair locks, they always cause trouble.
> After this can of worms that I need to fix regardless.
Sure.
| |